1. Field of the Invention
This invention relates to vegetation mats used for a process of growing plants on the clad surfaces of hills or river banks or other clad surfaces formed by road construction and land formation.
2. Description of the Prior Art
The clad surfaces noted above are usually made green by growing plants in order to protect them and maintain wanted scenery.
Such green clad surfaces are usually produced by using vegetation mats. Such vegetation mats are formed by using a growth base formed by mixing a soil improvement material, an organic fertilizer and a fertilization material, providing a jute fiber felt containing fertilizer on the lower clad surface of the growth base, wrapping the base and felt with a seed-containing cloth, which includes seeds provided between woven jute fiber cloth and cotton body, and sewing together the three components such that ridges are formed at a predetermined interval in the width direction (see, for instance, Japanese Utility Model Publication No. H3-20348).
In this prior art vegetation mat, however, the jute fiber felt that is held in contact with the clad surface is comparatively hard. Therefore, the vegetation mat is inferior in its familiarity with the clad surface, and it is liable that its back surface is locally spaced apart from the clad surface. Besides, the jute fiber felt takes a long time for its corrosion although it may contain water, that is, the soil improvement material, organic fertilizer and fertilization material do not easily fall onto the clad surface. Consequently, a gap is produced between the vegetation mat and clad surface, making it difficult for the seeds to root although they may bud, and therefore many of them will decay.
Further, where sole vegetation mats are used for making green surfaces, with corrosion and decomposition of the seed-containing cloth in a defective state of budding and growth of the seeds, the growth base will be frozen or flown away with rainfall. To cope with this, the vegetation mats provided on the clad surface are covered with nets, or each vegetation mat is provided in a state that it is accommodated in a bag-like mat holder section provided in it. However, the operation of providing such nets is complicated and cumbersome and requires a great deal of man-hours, thus leading to high process cost.